Porcine epidemic diarrhea virus inhibits dsRNA-induced interferon-ß production in porcine intestinal epithelial cells by blockade of the RIG-I-mediated pathway

Cao, Liyan; Ge, Xuying; Gao, Yu; Herrler, Georg; Ren, Yudong; Ren, Xiaofeng; Li, Guangxing

PEDV failed to induce IFN-β expression and inhibited poly (I:C)-mediated IFN-β production in IECs Type I IFNs (IFN-α/β) are critical to the host antiviral innate immune response. However, there is no evidence suggesting that IECs produce type I IFNs in response to PEDV infection. Previous studies have showed that PEDV could be propagated in IECs [ 23, 24,] . To confirm whether PEDV infection could induce IFN-β production in IECs or not, we transiently cotransfected the IFN-β/ luciferase reporter plasmid (IFN-β-Luc) and the Renilla luciferase construct phRL-TK and then infected with PEDV (at an MOI of 1 or 0.1, respectively) or mockinfected for 24 h. The cells were retransfected with 1 μg of poly (I:C) as a positive inducer. As shown in Fig. 1a , IFN-β luciferase activity enhanced markedly in positive controls, while it was almost not detected in PEDV-infected IECs. In addition, IFN-β mRNA expression was hardly detected in PEDV-infected IECs similar to mock-infected group, however, it had significant expression in poly (I:C)-transfected group at the indicated times (12 h and 24 h, p < 0.01) (Fig. 1b) . This result was consistent with the luciferase reporter assay. Taken together, PEDV infection of IECs did not induce IFN-β activation.